78 THE VITALITY AND GERMINATION OF SEEDS. 



mixture of ilhiminatint^ g-as and air. The increase in weight was only 

 0.04 per cent. An anah^sis of the inclosed gas was as follows: 



Per cent. 



Oxygen 3. 23 



Carl)on dioxid 1. 21 



Methane and nitrogen 95. 96 



{(l) Another 50-gram sample of onion seed, belonging to a different 

 series, was sealed in a bottle of 300 cc. capacity, and showed the 

 following composition of the inclosed air: 



Per cent. 



Oxygen 8.02 



Nitrogen - 85. 17 



Carbon dioxid - 6. 81 



In only one case was there an}^ deterioration in vitality, namely, 

 where the large quantity' of moisture was present. The other samples 

 germinated normally. The seed kept in the illuminating gas germi- 

 nated even better than the control. 



In all of the bottles there was a marked decrease in pressure, show- 

 ing that the volume of oxygen absorbed was much greater than the 

 volume of the carbon dioxid given off. 



During respiration certain chemical changes must be taking place 

 which exert a marked influence on the vitalitj' of seeds. What these 

 changes are is a question 3^et to be solved. The protoplasts of the 

 individual cells gradually but surely become disorganized. C. De 

 Candolle" takes the view, in discussing the experiments of Van Tieg- 

 hem and Bonnier, that during respiration life is simply subdued. 

 But the period of subdued activity, he saj^s, is comparatively short, 

 for respiration soon ceases and life becomes wholly latent. As a result 

 of his own experiments in storing seeds at low temperatures he con- 

 cludes that seeds cease to respire and become completely inert; in 

 which case they can suffer any degree of reduction in temperature 

 without being killed. The killing of the seeds experimented with 

 (lobelia) he attributes to the fact that the jjrotoplasm had not l)ecome 

 inert, but simpl}^ subdued, and the seeds were thus affected b}' the low 

 temperature. 



As a result of later experiments C De Candolle,* in keeping some 

 seeds under mercury to exclude air, concludes that " seeds can continue 

 to subsist in a condition of complete vital inertia, from which they 

 recover whenever the conditions of the surrounding medium permits 

 their 'energids,' or living masses of their cells, to respire and assim- 

 ilate." He compares the protoplasm in latent life to an explosive 

 mixture, having the facult}" of reviving whenever the conditions are 

 favorable. This comparison seems rather an unfortunate one; jet, 

 within a certain measure it is probabl}' true. 



"Revue Scientifique, ser. 4, 4: 321-326, 1895. 

 &Pop. Sci. Monthly, 51: 106-111, 1897. 



